#!/usr/bin/env bash
# dev.sh — start/stop the frontend (Nuxt), backend (Express) and the Lean
# editor server (lean4web via docker compose) together.
#
# Usage:
#   ./dev.sh                     Start everything in the foreground (Ctrl+C stops all)
#   ./dev.sh start               Start everything in the background
#   ./dev.sh stop                Stop everything
#   ./dev.sh restart             Stop then start
#   ./dev.sh status              Show what is running
#   ./dev.sh logs [service]      Follow logs (all, backend, frontend, or lean)
#
# backend and frontend are npm dev servers; lean is the Lean editor server
# from docker-compose.yml (see lean/). It is the heavy one — the image's
# first build fetches Mathlib — so dev.sh only rides along with docker: when
# docker is not available it says so and starts the other two regardless.

set -euo pipefail

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PID_DIR="$ROOT/.pids"
LOG_DIR="$ROOT/.logs"
COMPOSE="$ROOT/docker-compose.yml"
SERVICES=("backend" "frontend")
LEAN_LOG="$LOG_DIR/lean.log"

compose() { docker compose -f "$COMPOSE" "$@"; }

# The Lean server needs docker up, not just installed — probing the daemon
# keeps a dead docker socket from failing backend + frontend.
docker_ready() {
  command -v docker >/dev/null 2>&1 && docker info >/dev/null 2>&1
}

lean_running() {
  docker_ready && [[ -n "$(compose ps --status running --services 2>/dev/null | grep -x lean)" ]]
}

pid_of() {
  local pid_file="$PID_DIR/$1.pid"
  [[ -f "$pid_file" ]] && cat "$pid_file" || true
}

is_running() {
  local pid
  pid="$(pid_of "$1")"
  [[ -n "$pid" ]] && kill -0 "$pid" 2>/dev/null
}

start_service() {
  local name="$1"
  if is_running "$name"; then
    echo "$name is already running (PID $(pid_of "$name"))"
    return
  fi
  mkdir -p "$PID_DIR" "$LOG_DIR"
  # setsid puts each service in its own process group so `stop` can kill
  # npm and all of its child processes (node --watch, nuxt, ...) cleanly.
  setsid bash -c 'cd "$1" && exec npm run dev' _ "$ROOT/$name" \
    > "$LOG_DIR/$name.log" 2>&1 &
  local pid=$!
  echo "$pid" > "$PID_DIR/$name.pid"
  echo "started $name (PID $pid) — log: $LOG_DIR/$name.log"
}

# `up -d` also builds the image the first time it is asked for (heavy:
# Mathlib), so this rides in the background with its output to lean.log
# rather than holding `start` hostage to a cold build.
start_lean() {
  if lean_running; then
    echo "lean is already running (docker compose)"
    return
  fi
  if ! docker_ready; then
    echo "lean: docker is not available — skipping the Lean server (see lean/README.md)" >&2
    return
  fi
  mkdir -p "$LOG_DIR"
  setsid bash -c 'cd "$1" && exec docker compose -f "$2" up -d lean' _ "$ROOT" "$COMPOSE" \
    > "$LEAN_LOG" 2>&1 &
  echo "starting lean (docker compose) — log: $LEAN_LOG"
  echo "  (the first build fetches Mathlib and takes a while)"
}

stop_service() {
  local name="$1"
  local pid
  pid="$(pid_of "$name")"

  if ! is_running "$name"; then
    echo "$name is not running"
    rm -f "$PID_DIR/$name.pid"
    return
  fi

  # Negative PID kills the whole process group (npm + its children).
  kill -TERM -- "-$pid" 2>/dev/null || kill -TERM "$pid" 2>/dev/null || true
  # Wait up to 5s for a graceful shutdown, then force-kill.
  for _ in {1..50}; do
    kill -0 "$pid" 2>/dev/null || break
    sleep 0.1
  done
  if kill -0 "$pid" 2>/dev/null; then
    kill -KILL -- "-$pid" 2>/dev/null || kill -KILL "$pid" 2>/dev/null || true
  fi
  rm -f "$PID_DIR/$name.pid"
  echo "stopped $name (PID $pid)"
}

# `stop`, not `down` — the container is kept (like a stopped dev server),
# and `docker compose down` stays the maintainer's call.
stop_lean() {
  if ! lean_running; then
    echo "lean is not running"
    return
  fi
  compose stop lean >/dev/null 2>&1 || true
  echo "stopped lean (docker compose)"
}

status() {
  for name in "${SERVICES[@]}"; do
    if is_running "$name"; then
      echo "$name: running (PID $(pid_of "$name"))"
    else
      echo "$name: stopped"
    fi
  done
  if lean_running; then
    echo "lean: running (docker compose)"
  elif docker_ready; then
    echo "lean: stopped"
  else
    echo "lean: stopped (docker is not available)"
  fi
}

FG_PIDS=()
LEAN_PID=""
SHUTTING=0

# Stop all foreground services (and their process groups). A second call
# (e.g. pressing Ctrl+C again while shutting down) escalates to SIGKILL.
fg_stop_all() {
  local name pid sig=TERM
  if [[ $SHUTTING -eq 1 ]]; then sig=KILL; else
    SHUTTING=1
    echo
    echo "stopping backend + frontend + lean..."
  fi
  for pid in "${FG_PIDS[@]:-}"; do
    kill -"$sig" -- "-$pid" 2>/dev/null || kill -"$sig" "$pid" 2>/dev/null || true
  done
  if [[ -n "$LEAN_PID" ]]; then
    kill -"$sig" -- "-$LEAN_PID" 2>/dev/null || kill -"$sig" "$LEAN_PID" 2>/dev/null || true
    # belt and braces: if the compose client died before telling dockerd,
    # the container is still up — `stop` is quick and idempotent.
    docker_ready && compose stop lean >/dev/null 2>&1 || true
  fi
  wait 2>/dev/null || true
  for name in "${SERVICES[@]}"; do rm -f "$PID_DIR/$name.pid"; done
  exit 0
}

foreground() {
  local name
  for name in "${SERVICES[@]}"; do
    if is_running "$name"; then
      echo "$name is already running (PID $(pid_of "$name")); run '$0 stop' first" >&2
      exit 1
    fi
  done
  mkdir -p "$PID_DIR"
  for name in "${SERVICES[@]}"; do
    # setsid puts each service in its own process group (PID == PGID) so the
    # output prefix pipeline survives the shutdown; sed -u tags every line.
    setsid bash -c 'cd "$1" && exec npm run dev' _ "$ROOT/$name" \
      > >(sed -u "s/^/[$name] /") 2>&1 &
    local pid=$!
    FG_PIDS+=("$pid")
    echo "$pid" > "$PID_DIR/$name.pid"
  done
  # The Lean server rides along the same way — compose `up` streams its
  # build/run output, tagged. But the pair stays in charge: lean's absence
  # (no docker) or its failure (no image, daemon flake) never takes them
  # down, so `wait -n` watches only the npm services.
  if docker_ready; then
    setsid bash -c 'cd "$1" && exec docker compose -f "$2" up lean' _ "$ROOT" "$COMPOSE" \
      > >(sed -u "s/^/[lean] /") 2>&1 &
    LEAN_PID=$!
  else
    echo "[lean] docker is not available — running without the Lean server (see lean/README.md)" >&2
  fi
  trap 'fg_stop_all' INT TERM
  echo "backend + frontend running (lean if docker allows) — press Ctrl+C to stop all"
  # Exit as soon as either dev server dies, so they always run/stop together.
  wait -n "${FG_PIDS[@]}"
  echo "a dev server exited — stopping the others..."
  fg_stop_all
}

case "${1:-dev}" in
  dev)
    foreground
    ;;
  start)
    for name in "${SERVICES[@]}"; do start_service "$name"; done
    start_lean
    echo
    echo "backend:  http://localhost:5000"
    echo "frontend: http://localhost:3000"
    echo "lean:     http://localhost:8080 (docker compose) — the wiki frames it at /lean"
    ;;
  stop)
    for name in "${SERVICES[@]}"; do stop_service "$name"; done
    stop_lean
    ;;
  restart)
    for name in "${SERVICES[@]}"; do stop_service "$name"; done
    stop_lean
    for name in "${SERVICES[@]}"; do start_service "$name"; done
    start_lean
    ;;
  status)
    status
    ;;
  logs)
    case "${2:-all}" in
      # `all` mixes the file logs with the container's — lean lives in
      # docker, not in a dev.log, once it is up.
      all)
        if docker_ready; then
          compose logs -f lean &
          LEAN_LOG_PID=$!
          trap 'kill "$LEAN_LOG_PID" 2>/dev/null || true' INT TERM
        fi
        tail -f "$LOG_DIR"/*.log
        ;;
      backend|frontend) tail -f "$LOG_DIR/$2.log" ;;
      lean)
        if docker_ready; then compose logs -f lean; else echo "docker is not available" >&2; exit 1; fi
        ;;
      *) echo "usage: $0 logs [all|backend|frontend|lean]"; exit 1 ;;
    esac
    ;;
  *)
    echo "usage: $0 [dev|start|stop|restart|status|logs [all|backend|frontend|lean]]  (default: dev)"
    exit 1
    ;;
esac